Method and system for magnetic actuated milling for pigment dispersions

ABSTRACT

A method for preparing a pigment dispersion includes a) adding a pigment, a surfactant, and a solvent into a vessel, b) adding magnetic particles into the vessel; and c) applying a varying magnetic field to move the magnetic particles to mill down pigment particle size. A system for preparing a pigment dispersion includes a) a vessel for holding a solution comprising pigment particles, a surfactant and a solvent, b) magnetic particles added to the solution, c) a source for applying a varying magnetic field to move the magnetic particles to mill down pigment particle size, and d) a collector for collecting the magnetic particles for re-using at a later time.

CROSS-REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly owned and U.S. patent application Ser. No.13/860,466 entitled “METHOD AND SYSTEM FOR MAGNETIC ACTUATED MIXING” toYu Liu et al., electronically filed on the same day herewith; andcommonly owned and co-pending, U.S. patent application Ser. No.13/860,474, now U.S. Pat. No. 8,871,420 knot yet-assigned) entitled“METHOD AND SYSTEM FOR MAGNETIC ACTUATED MIXING TO PREPARE LATEXEMULSION” to Yu Liu et al., electronically filed on the same dayherewith.

BACKGROUND

The presently disclosed embodiments relate generally to a method formagnetic actuated milling which uses magnetic particles and magneticfield to facilitate the pigment dispersions useful in making tonersuitable for electrophotographic apparatuses.

Numerous processes are within the purview of those skilled in the artfor the preparation of toners. Emulsion aggregation (EA) is one suchmethod.

The pigment dispersion is an important component in the preparation ofEA toner. In order for pigment particles to form aggregates with thelatex particles, the pigment particles should have size smaller or atleast a size comparable to the latex particles, preferably between about5 and 300 nanometers in diameter. Conventional mechanical impellermilling system loses its efficiency throughout the whole reactionvessel. For pigment dispersion utilizing an in-line rotor-stator typehomogenizer; the length of process time exceeds four hours. It has alsobeen generally accepted that mechanical components has main concerns onmaintenance including: large consumption of solvents for cleaning;frequent pumping in/out for cleaning pumps/pipelines; anti-resonancedesign to layout system, floor space and flexibility. Furthermore, thesesystems are working on macro-scale bulk shearing and are not ideal forpreparing small size particle especially in the size range of nanometerand submicron, which is a typical range of pigment particles used as anEA toner component. Therefore, micro-scale driven milling could bepreferable.

There remains a need to develop a dispersion technology which reducesprocessing time and cost, without sacrificing benchmark materialproperties (e.g., small size and narrow particle size distribution).

SUMMARY

In embodiments, there is provided a method for preparing a pigmentdispersion includes a) adding a pigment, a surfactant, and a solventinto a vessel, b) adding magnetic particles into the vessel; and c)applying a varying magnetic field to move the magnetic particles to milldown pigment particle size.

Another embodiment provides a system for preparing a pigment dispersionincludes a) a vessel for holding a solution comprising pigmentparticles, a surfactant and a solvent, b) magnetic particles added tothe solution, c) a source for applying a varying magnetic field to movethe magnetic particles to mill down pigment particle size, and d) acollector for collecting the magnetic particles for re-using at a latertime.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present embodiments, reference may bemade to the accompanying figures.

FIG. 1 is a diagram of a magnetic actuated mixing system in accordancewith the present embodiments;

FIG. 2 is a flow chart illustrating a method for preparing a pigmentdispersion in accordance with the present embodiments;

FIG. 3 is a graph illustrating particle size and particle sizedistribution of a pigment dispersion made in accordance with aconventional method;

FIG. 4 is a graph illustrating particle size and particle sizedistribution of the pigment dispersion made in accordance with thepresent embodiments;

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings, which form a part hereof and which illustrate severalembodiments. It is understood that other embodiments may be utilized andstructural and operational changes may be made without departure fromthe scope of the present disclosure. The same reference numerals areused to identify the same structure in different figures unlessspecified otherwise. The structures in the figures are not drawnaccording to their relative proportions and the drawings should not beinterpreted as limiting the disclosure in size, relative size, orlocation.

Processing

Pigment dispersions are often used in the preparation of EA toners. Thepresent embodiments provide for the use of magnetic actuating chaoticmotion of magnetic particles to prepare pigment dispersions as providedby both mixing and milling capabilities at nano or micro scale. Theseembodiments apply cyclic magnetic field to drive the chaotic motion ofthe magnetic particles to provide consistent nano or micro scaleshearing throughout the entire vessel, thus providing uniform dispersionof materials within a very short time frame (e.g., minutes). The presentembodiments further eliminate the need for complex layouts of pipes,pumps, impellers, and material transfer commonly required for thepreparation of pigment dispersions. Moreover, the present method isgeneric for any type or geometry design of reaction vessels, and can bereadily optimized to fit any set up.

As shown in FIG. 1, there is provided a milling system 45 comprisingmagnetic particles 50 loaded in a solution 55 which is moved to actuatepigment dispersion by the periodic variation of a magnetic field 60applied to the magnetic particles 50. The magnetic particles may bepre-loaded or filled into the vessel 70 when milling is needed. Themagnetic field 60 is applied through electromagnets 65 on either side ofthe vessel 70. The system 45 achieves intense micro shearing fields 75uniformly on the pigment particles throughout the vessel 70. Themagnetic particles under the varying magnetic field are also impactingon the pigment particles. The magnetic particles can be successfullycollected and recycled by a magnet for subsequent applications.

In embodiments, there is provided a method for preparing pigmentdispersions using magnetic actuated mixing 135 as shown in FIG. 2. A drypigment is loaded in a solvent, such as water, an organic solvent ormixtures thereof, into the vessel at step 140. In embodiments, thepigment is selected from the group consisting of a blue pigment, a blackpigment, a cyan pigment, a brown pigment, a green pigment, a whitepigment, a violet pigment, a magenta pigment, a red pigment, an orangepigment, a yellow pigment, and mixtures thereof. In one embodiment, thepigment is carbon black. In embodiments, the pigment/water mixturecomprises the pigment and water in a weight ratio of from about 5% toabout 80%, or from about 10% to about 50%, or from about 15% to about25%.

The magnetic particles may be comprised of, paramagnetic, ferrimagnetic,ferromagnetic or antiferromagnetic materials. The magnetic particles mayfurther be comprised of a material selected from the group consisting ofFe, Fe₂O₃, Ni, CrO₂, Cs, and the like or mixtures thereof. Inembodiments, the magnetic particles have a non-magnetic coating. Inother embodiments, the magnetic particles can also be encapsulated witha shell, for example, a polymeric shell comprising, in embodiments,polystyrene, polyvinyl chloride, TEFLON®, PMMA, and the like andmixtures thereof. The magnetic particles may have a diameter of fromabout 5 nm to about 50 μm, or from about 10 nm to about 10 μm, or fromabout 100 nm to about 5 μm. The volume percentage of magnetic particlescan be chosen based on different applications or processes. Inembodiments, the volume percentage of magnetic particles used formilling may also vary depending on the different application or processfor which the pigment particles are being used. For example, from about5% to about 80%, or from about 10% to about 50%, or from about 15% toabout 25% magnetic particles may be added to the vessel. The magneticfield may have a strength of from about 500 Gauss to about 50,000 Gauss,or from about 1000 Gauss to about 20,000 Gauss, or from about 2000 Gaussto about 15,000 Gauss. In embodiments, the electromagnets may becircularly patterned with a uniform angular spacing. In embodiments, theelectromagnets are used to apply the varying (switchable) magnetic fieldin a circular motion on a micro or nano scale. The magnetic field mayalso be applied in an up and down, or left and right, or triangularmotion. In specific embodiments, the varying magnetic field is appliedby moving a permanent magnet. In embodiments, the varying magnetic fieldis biased by another constant magnetic field. The flexible system setupis not limited by the geometry of vessel 80. The present embodiments areable to drive chaotic or random motion of magnetic particles across thewhole solution at a micro scale. This type of random motion generatesmaximized shearing and impacting effects on the pigment particles andhelps facilitate a uniform milling of the materials to achieve requiredparticle size. The milling is efficient and uniform across the entirevessel because of the uniform magnetic field distribution with littledependence on distance from the field source. If micro sized magneticparticles are used, due to the large surface contact area between micromagnetic particles and the solution, micro milling due to enhanced localinteractions significantly produces homogeneous and global milling. Thepresent embodiments thus provide small particles on the nano to microscale and uniform distribution. The present embodiments also provide forthe potential of higher viscosity (for example, a viscosity of fromabout 0.1 cP to about 100,000 cP at 25° C.) mixing if the exposedmagnetic field is large.

Another advantage of the present method and system is the fact that itis free of mechanical components and thus maintenance, whichsignificantly reduces the cost of the system. The present embodimentsare also free of noise.

Referring back to FIG. 2, the vessel may have the magnetic particlesalready pre-loaded in the vessel or the magnetic particles may be loadedinto the vessel after the pigment/water mixture at step 145. Asurfactant may then be added to the pigment/water mixture in the vesselat step 150. In embodiments, the surfactant is selected from the groupconsisting of anionic surfactants, nonionic surfactants, cationicsurfactants, and combinations thereof. A magnetic field is generated andapplied to the mixture and magnetic particles in the vessel at step 155.A pigment dispersion with the desired particle size is then achieved bycontinued mixing of the magnetic particles through application of themagnetic field. A reduction in pigment particles at step 160 is achievedwith continued mixing. The duration and speed of mixing will bedependent on the pigment particle size desired. In embodiments, thepigment particle size achieved is from about 5 nm to about 300 nm, orfrom about 10 nm to about 200 nm, or from about 100 nm to about 150 nm.The magnetic particles can then be collected for re-use at step 165.

Resins for Preparing Toners

In embodiments, the pigment dispersion made by methods disclosed hereincan be used to prepare a toner comprising a resin composition.

The resin composition may comprise one or more resins, such as two ormore resins. The total amount of resin in the resin composition can befrom about 1% to 99%, such as from about 10% to about 95%, or from about20% to 90% by weight of the resin composition.

A resin used in the method disclosed herein may be any latex resinutilized in forming Emulsion Aggregation (EA) toners. Such resins, inturn, may be made of any suitable monomer. Any monomer employed may beselected depending upon the particular polymer to be used. Two maintypes of EA methods for making toners are known. First is an EA processthat forms acrylate based, e.g., styrene acrylate, toner particles. See,for example, U.S. Pat. No. 6,120,967, incorporated herein by referencein its entirety, as one example of such a process. Second is an EAprocess that forms polyester, e.g., sodio sulfonated polyester. See, forexample, U.S. Pat. No. 5,916,725, incorporated herein by reference inits entirety, as one example of such a process.

Illustrative examples of latex resins or polymers selected for thenon-crosslinked resin and crosslinked resin or gel include, but are notlimited to, styrene acrylates, styrene methacrylates, butadienes,isoprene, acrylonitrile, acrylic acid, methacrylic acid, beta-carboxyethyl arylate, polyesters, known polymers such aspoly(styrene-butadiene), poly(methyl styrene-butadiene), poly(methylmethacrylate-butadiene), poly(ethyl methacrylate-butadiene), poly(propylmethacrylate-butadiene), poly(butyl methacrylate-butadiene), poly(methylacrylate-butadiene), poly(ethyl acrylate-butadiene), poly(propylacrylate-butadiene), poly(butyl acrylate-butadiene),poly(styrene-isoprene), poly(methyl styrene-isoprene), poly(methylmethacrylate-isoprene), poly(ethyl methacrylate-isoprene), poly(propylmethacrylate-isoprene), poly(butyl methacrylate-isoprene), poly(methylacrylate-isoprene), poly(ethyl acrylate-isoprene), poly(propylacrylate-isoprene), poly(butyl acrylate-isoprene); poly(styrene-propylacrylate), poly(styrene-butyl acrylate), poly(styrene-butadiene-acrylicacid), poly(styrene-butadiene-methacrylic acid), poly(styrene-butylacrylate-acrylic acid), poly(styrene-butyl acrylate-methacrylic acid),poly(styrene-butyl acrylate-acrylonitrile), poly(styrene-butylacrylate-acrylonitrile-acrylic acid), and the like, and mixturesthereof. The resin or polymer can be a styrene/butyl acrylate/carboxylicacid terpolymer. At least one of the resin substantially free ofcrosslinking and the crosslinked resin can comprise carboxylic acid inan amount of from about 0.05 to about 10 weight percent based upon thetotal weight of the resin substantially free of cross linking orcrosslinked resin.

The monomers used in making the selected polymer are not limited, andthe monomers utilized may include any one or more of, for example,styrene, acrylates such as methacrylates, butylacrylates, β-carboxyethyl acrylate (β-CEA), etc., butadiene, isoprene, acrylic acid,methacrylic acid, itaconic acid, acrylonitrile, benzenes such asdivinylbenzene, etc., and the like. Known chain transfer agents, forexample dodecanethiol or carbon tetrabromide, can be utilized to controlthe molecular weight properties of the polymer. Any suitable method forforming the latex polymer from the monomers may be used withoutrestriction.

The resin that is substantially free of cross linking (also referred toherein as a non-crosslinked resin) can comprise a resin having less thanabout 0.1 percent cross linking. For example, the non-crosslinked latexcan comprise styrene, butylacrylate, and beta-carboxy ethyl acrylate(beta-CEA) monomers, although not limited to these monomers, termedherein as monomers A, B, and C, prepared, for example, by emulsionpolymerization in the presence of an initiator, a chain transfer agent(CTA), and surfactant.

The resin substantially free of cross linking can comprisestyrene:butylacrylate:beta-carboxy ethyl acrylate wherein, for example,the non-crosslinked resin monomers can be present in an amount of about70 percent to about 90 percent styrene, about 10 percent to about 30percent butylacrylate, and about 0.05 parts per hundred to about 10parts per hundred beta-CEA, or about 3 parts per hundred beta-CEA, byweight based upon the total weight of the monomers, although notlimited. For example, the carboxylic acid can be selected, for example,from the group comprised of, but not limited to, acrylic acid,methacrylic acid, itaconic acid, beta carboxy ethyl acrylate (beta CEA),fumaric acid, maleic acid, and cinnamic acid.

In a feature herein, the non-crosslinked resin can comprise about 73percent to about 85 percent styrene, about 27 percent to about 15percent butylacrylate, and about 1.0 part per hundred to about 5 partsper hundred beta-CEA, by weight based upon the total weight of themonomers although the compositions and processes are not limited tothese particular types of monomers or ranges. In another feature, thenon-crosslinked resin can comprise about 81.7 percent styrene, about18.3 percent butylacrylate and about 3.0 parts per hundred beta-CEA byweight based upon the total weight of the monomers.

The initiator can be, for example, but is not limited to, sodium,potassium or ammonium persulfate and can be present in the range of, forexample, about 0.5 to about 3.0 percent based upon the weight of themonomers, although not limited. The CTA can be present in an amount offrom about 0.5 to about 5.0 percent by weight based upon the combinedweight of the monomers A and B, although not limited. The surfactant canbe an anionic surfactant present in the range of from about 0.7 to about5.0 percent by weight based upon the weight of the aqueous phase,although not limited to this type or range.

The resin can be a polyester resin such as an amorphous polyester resin,a crystalline polyester resin, and/or a combination thereof. The polymerused to form the resin can be a polyester resin described in U.S. Pat.Nos. 6,593,049 and 6,756,176, the disclosures of each of which arehereby incorporated by reference in their entirety. Suitable resins alsoinclude a mixture of an amorphous polyester resin and a crystallinepolyester resin as described in U.S. Pat. No. 6,830,860, the disclosureof which is hereby incorporated by reference in its entirety.

The resin can be a polyester resin formed by reacting a diol with adiacid in the presence of an optional catalyst. For forming acrystalline polyester, suitable organic diols include aliphatic diolswith from about 2 to about 36 carbon atoms, such as 1,2-ethanediol,1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol,1,12-dodecanediol and the like; alkali sulfo-aliphatic diols such assodio 2-sulfo-1,2-ethanediol, lithio 2-sulfo-1,2-ethanediol, potassio2-sulfo-1,2-ethanediol, sodio 2-sulfo-1,3-propanediol, lithio2-sulfo-1,3-propanediol, potassio 2-sulfo-1,3-propanediol, mixturethereof, and the like. The aliphatic diol may be, for example, selectedin an amount of from about 40 to about 60 mole percent, such as fromabout 42 to about 55 mole percent, or from about 45 to about 53 molepercent (although amounts outside of these ranges can be used), and thealkali sulfo-aliphatic diol can be selected in an amount of from about 0to about 10 mole percent, such as from about 1 to about 4 mole percentof the resin (although amounts outside of these ranges can be used).

Examples of organic diacids or diesters including vinyl diacids or vinyldiesters selected for the preparation of the crystalline resins includeoxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid,azelaic acid, sebacic acid, fumaric acid, dimethyl fumarate, dimethylitaconate, cis, 1,4-diacetoxy-2-butene, diethyl fumarate, diethylmaleate, phthalic acid, isophthalic acid, terephthalic acid,naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid,cyclohexane dicarboxylic acid, malonic acid and mesaconic acid, adiester or anhydride thereof; and an alkali sulfo-organic diacid such asthe sodio, lithio or potassio salt of dimethyl-5-sulfo-isophthalate,dialkyl-5-sulfo-isophthalate-4-sulfo-1,8-naphthalic anhydride,4-sulfo-phthalic acid, dimethyl-4-sulfo-phthalate,dialkyl-4-sulfo-phthalate, 4-sulfophenyl-3,5-dicarbomethoxybenzene,6-sulfa-2-naphthyl-3,5-dicarbomethoxybenzene, sulfo-terephthalic acid,dimethyl-sulfo-terephthalate, 5-sulfo-isophthalic acid,dialkyl-sulfo-terephthalate, sulfoethanediol, 2-sulfopropanediol,2-sulfobutanediol, 3-sulfopentanediol, 2-sulfohexanediol,3-sulfo-2-methylpentanediol, 2-sulfo-3,3-dimethylpentanediol,sulfa-p-hydroxybenzoic acid, N,N-bis(2-hydroxyethyl)-2-amino ethanesulfonate, or mixtures thereof. The organic diacid may be selected in anamount of, for example, from about 40 to about 60 mole percent, inembodiments from about 42 to about 52 mole percent, such as from about45 to about 50 mole percent (although amounts outside of these rangescan be used), and the alkali sulfo-aliphatic diacid can be selected inan amount of from about 1 to about 10 mole percent of the resin(although amounts outside of these ranges can be used).

Examples of crystalline resins include polyesters, polyamides,polyimides, polyolefins, polyethylene, polybutylene, polyisobutyrate,ethylene-propylene copolymers, ethylene-vinyl acetate copolymers,polypropylene, mixtures thereof, and the like. Specific crystallineresins may be polyester based, such as poly(ethylene-adipate),poly(propylene-adipate), poly(butylene-adipate),poly(pentylene-adipate), poly(hexylene-adipate), poly(octylene-adipate),poly(ethylene-succinate), poly(propylene-succinate),poly(butylene-succinate), poly(pentylene-succinate),poly(hexylene-succinate), poly(octylene-succinate),poly(ethylene-sebacate), poly(propylene-sebacate),poly(butylene-sebacate), poly(pentylene-sebacate),poly(hexylene-sebacate), poly(octylene-sebacate),poly(decylene-sebacate), poly(decylene-decanoate),poly(ethylene-decanoate), poly(ethylene dodecanoate),poly(nonylene-sebacate), poly(nonylene-decanoate),copoly(ethylene-fumarate)-copoly(ethylene-sebacate),copoly(ethylene-fumarate)-copoly(ethylene-decanoate),copoly(ethylene-fumarate)-copoly(ethylene-dodecanoate), alkalicopoly(5-sulfoisophthaloyl)-copoly(ethylene-adipate), alkalicopoly(5-sulfoisophthaloyl)-copoly(propylene-adipate), alkalicopoly(5-sulfoisophthaloyl)-copoly(butylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate), alkalicopoly(5-sulfoisophthaloyl)-copoly(ethylene-succinate), alkalicopoly(5-sulfoisophthaloyl)-copoly(propylene-succinate), alkalicopoly(5-sulfoisophthaloyl)-copoly(butylenes-succinate), alkalicopoly(5-sulfoisophthaloyl)-copoly(pentylene-succinate), alkalicopoly(5-sulfoisophthaloyl)-copoly(hexylene-succinate), alkalicopoly(5-sulfoisophthaloyl)-copoly(octylene-succinate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(ethylene-sebacate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(propylene-sebacate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(butylene-sebacate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(pentylene-sebacate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(hexylene-sebacate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(octylene-sebacate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkalicopoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate),poly(octylene-adipate), wherein alkali is a metal like sodium, lithiumor potassium. Examples of polyamides include poly(ethylene-adipamide),poly(propylene-adipamide), poly(butylenes-adipamide),poly(pentylene-adipamide), poly(hexylene-adipamide),poly(octylene-adipamide), poly(ethylene-succinimide), andpoly(propylene-sebecamide). Examples of polyimides includepoly(ethylene-adipimide), poly(propylene-adipimide),poly(butylene-adipimide), poly(pentylene-adipimide),poly(hexylene-adipimide), poly(octylene-adipimide),poly(ethylene-succinimide), poly(propylene-succinimide), andpoly(butylene-succinimide).

The crystalline resin can be present, for example, in an amount of fromabout 5 to about 50 percent by weight of the toner components, such asfrom about 10 to about 35 percent by weight of the toner components(although amounts outside of these ranges can be used). The crystallineresin can possess various melting points of, for example, from about 30°C. to about 120° C., in embodiments from about 50° C. to about 90° C.(although melting points outside of these ranges can be obtained). Thecrystalline resin can have a number average molecular weight (Mn), asmeasured by gel permeation chromatography (GPC) of, for example, fromabout 1,000 to about 50,000, such as from about 2,000 to about 25,000(although number average molecular weights outside of these ranges canbe obtained), and a weight average molecular weight (Mw) of, forexample, from about 2,000 to about 100,000, such as from about 3,000 toabout 80,000 (although weight average molecular weights outside of theseranges can be obtained), as determined by Gel Permeation Chromatographyusing polystyrene standards. The molecular weight distribution (Mw/Mn)of the crystalline resin can be, for example, from about 2 to about 6,in embodiments from about 3 to about 4 (although molecular weightdistributions outside of these ranges can be obtained).

Examples of diacids or diesters including vinyl diacids or vinyldiesters used for the preparation of amorphous polyesters includedicarboxylic acids or diesters such as terephthalic acid, phthalic acid,isophthalic acid, fumaric acid, dimethyl fumarate, dimethyl itaconate,cis, 1,4-diacetoxy-2-butene, diethyl fumarate, diethyl maleate, maleicacid, succinic acid, itaconic acid, succinic acid, succinic anhydride,dodecylsuccinic acid, dodecylsuccinic anhydride, glutaric acid, glutaricanhydride, adipic acid, pimelic acid, suberic acid, azelaic acid,dodecane diacid, dimethyl terephthalate, diethyl terephthalate,dimethylisophthalate, diethylisophthalate, dimethylphthalate, phthalicanhydride, diethylphthalate, dimethylsuccinate, dimethylfumarate,dimethylmaleate, dimethylglutarate, dimethyladipate, dimethyldodecylsuccinate, and combinations thereof. The organic diacid ordiester can be present, for example, in an amount from about 40 to about60 mole percent of the resin, such as from about 42 to about 52 molepercent of the resin, or from about 45 to about 50 mole percent of theresin (although amounts outside of these ranges can be used).

Examples of diols that can be used in generating the amorphous polyesterinclude 1,2-propanediol, 1,3-propanediol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, pentanediol, hexanediol,2,2-dimethylpropanediol, 2,2,3-trimethylhexanediol, heptanediol,dodecanediol, bis(hydroxyethyl)-bisphenol A,bis(2-hydroxypropyl)-bisphenol A, 1,4-cyclohexanedimethanol,1,3-cyclohexanedimethanol, xylenedimethanol, cyclohexanediol, diethyleneglycol, bis(2-hydroxyethyl)oxide, dipropylene glycol, dibutylene, andcombinations thereof. The amount of organic diol selected can vary, andcan be present, for example, in an amount from about 40 to about 60 molepercent of the resin, such as from about 42 to about 55 mole percent ofthe resin, or from about 45 to about 53 mole percent of the resin(although amounts outside of these ranges can be used).

Polycondensation catalysts which may be used in forming either thecrystalline or amorphous polyesters include tetraalkyl titanates,dialkyltin oxides such as dibutyltin oxide, tetraalkyltins such asdibutyltin dilaurate, and dialkyltin oxide hydroxides such as butyltinoxide hydroxide, aluminum alkoxides, alkyl zinc, dialkyl zinc, zincoxide, stannous oxide, or combinations thereof. Such catalysts may beused in amounts of, for example, from about 0.01 mole percent to about 5mole percent based on the starting diacid or diester used to generatethe polyester resin (although amounts outside of this range can beused).

Suitable amorphous resins include polyesters, polyamides, polyimides,polyolefins, polyethylene, polybutylene, polyisobutyrate,ethylene-propylene copolymers, ethylene-vinyl acetate copolymers,polypropylene, combinations thereof, and the like. Examples of amorphousresins which may be used include alkali sulfonated-polyester resins,branched alkali sulfonated-polyester resins, alkali sulfonated-polyimideresins, and branched alkali sulfonated-polyimide resins. Alkalisulfonated polyester resins may be useful in embodiments, such as themetal or alkali salts ofcopoly(ethylene-terephthalate)-copoly(ethylene-5-sulfo-isophthalate),copoly(propylene-terephthalate)-copoly(propylene-5-sulfo-isophthalate),copoly(diethylene-terephthalate)-copoly(diethylene-5-sulfo-isophthalate),copoly(propylene-diethylene-terephthalate)-copoly(propylene-diethylene-5-sulfoisophthalate),copoly(propylene-butylene-terephthalate)-copoly(propylene-butylene-5-sulfoisophthalate),copoly propoxylated bisphenol-A-fumarate)-copoly(propoxylated bisphenolA-5-sulfo-isophthalate), copoly(ethoxylatedbisphenol-A-fumarate)-copoly(ethoxylatedbisphenol-A-5-sulfo-isophthalate), and copoly(ethoxylatedbisphenol-A-maleate)-copoly(ethoxylatedbisphenol-A-5-sulfo-isophthalate), wherein the alkali metal is, forexample, a sodium, lithium or potassium ion.

An unsaturated amorphous polyester resin can be used as a latex resin.Examples of such resins include those disclosed in U.S. Pat. No.6,063,827, the disclosure of which is hereby incorporated by referencein its entirety. Exemplary unsaturated amorphous polyester resinsinclude, but are not limited to, poly(propoxylated bisphenolco-fumarate), poly(ethoxylated bisphenol co-fumarate),poly(butyloxylated bisphenol co-fumarate), poly(co-propoxylatedbisphenol co-ethoxylated bisphenol co-fumarate), poly(1,2-propylenefumarate), poly(propoxylated bisphenol co-maleate), poly(ethoxylatedbisphenol co-maleate), poly(butyloxylated bisphenol co-maleate),poly(co-propoxylated bisphenol co-ethoxylated bisphenol co-maleate),poly(1,2-propylene maleate), poly(propoxylated bisphenol co-itaconate),poly(ethoxylated bisphenol co-itaconate), poly(butyloxylated bisphenolco-itaconate), poly(co-propoxylated bisphenol co-ethoxylated bisphenolco-itaconate), poly(1,2-propylene itaconate), and combinations thereof.A suitable polyester resin can be a polyalkoxylated bisphenolA-co-terephthalic acid/dodecenylsuccinic acid/trimellitic acid resin, ora polyalkoxylated bisphenol A-co-terephthalic acid/fumaricacid/dodecenylsuccinic acid resin, or a combination thereof.

Such amorphous resins can have a weight average molecular weight (Mw) offrom about 10,000 to about 100,000, such as from about 15,000 to about80,000.

An example of a linear propoxylated bisphenol a fumarate resin that canbe used as a latex resin is available under the trade name SPARII fromResana S/A Industrias Quimicas, Sao Paulo Brazil. Other propoxylatedbisphenol a fumarate resins that can be used and are commerciallyavailable include GTUF and FPESL-2 from Kao Corporation, Japan, andEM181635 from Reichhold, Research Triangle Park, N.C., and the like.

Suitable crystalline resins that can be used, optionally in combinationwith an amorphous resin as described above, include those disclosed inU.S. Patent Application Publication No. 2006/0222991, the disclosure ofwhich is hereby incorporated by reference in its entirety. Inembodiments, a suitable crystalline resin can include a resin formed ofdodecanedioic acid and 1,9-nonanediol.

Such crystalline resins can have a weight average molecular weight (Mw)of from about 10,000 to about 100,000, such as from about 14,000 toabout 30,000.

For example, a polyalkoxylated bisphenol A-co-terephthalicacid/dodecenylsuccinic acid/trimellitic acid resin, or a polyalkoxylatedbisphenol A-co-terephthalic acid/fumaric acid/dodecenylsuccinic acidresin, or a combination thereof, can be combined with apolydodecanedioic acid-co-1,9-nonanediol crystalline polyester resin.

The resins can have a glass transition temperature of from about 30° C.to about 80° C., such as from about 35° C. to about 70° C. The resinscan have a melt viscosity of from about 10 to about 1,000,000 Pa*S atabout 130° C., such as from about 20 to about 100,000 Pa*S. One, two, ormore toner resins may be used. Where two or more toner resins are used,the toner resins can be in any suitable ratio (e.g., weight ratio) suchas, for instance, about 10 percent (first resin)/90 percent (secondresin) to about 90 percent (first resin)/10 percent (second resin). Theresin can be formed by emulsion polymerization methods.

The resin can be formed at elevated temperatures of from about 30° C. toabout 200° C., such as from about 50° C. to about 150° C., or from about70° C. to about 100° C. However, the resin can also be formed at roomtemperature.

Stirring may be used to enhance formation of the resin. Any suitablestirring device may be used. In embodiments, the stirring speed can befrom about 10 revolutions per minute (rpm) to about 5,000 rpm, such asfrom about 20 rpm to about 2,000 rpm, or from about 50 rpm to about1,000 rpm. The stirring speed can be constant or the stirring speed canbe varied. For example, as the temperature becomes more uniformthroughout the mixture, the stirring speed can be increased. However, nomechanical or magnetic agitation is necessary in the method disclosedherein.

Solvent

Any suitable organic solvent can be contacted with the resin in theresin composition to help dissolve the resin in the resin composition.Suitable organic solvents for the methods disclosed herein includealcohols, such as methanol, ethanol, isopropanol, butanol, as well ashigher homologs and polyols, such as ethylene glycol, glycerol,sorbitol, and the like; ketones, such as acetone, 2-butanone,2-pentanone, 3-pentanone, ethyl isopropyl ketone, methyl isobutylketone, diisobutyl ketone, and the like; amides, such asdimethylformamide, dimethylacetamide, N-methylpyrrolidone,1,2-dimethyl-2-imidazolidinone, and the like; nitriles, such asacetonitrile, propionitrile, butyronitrile, isobutyronitrile,valeronitrile, benzonitrile, and the like; ethers, such as ditertbutylether, dimethoxyethane, 2-methoxyethyl ether, 1,4-dioxane,tetrahydrohyran, morpholine, and the like; sulfones, such asmethylsulfonylmethane, sulfolane, and the like; sulfoxides, such asdimethylsulfoxide; phosphoramides, such as hexamethylphosphoramide;benzene and benzene derivatives; as well as esters, amines andcombinations thereof, in an amount of, for example from about 1 wt % to99 wt %, from about 20 wt % to 80 wt %, or from about 20 wt % to about50 wt %.

The organic solvent can be immiscible in water and can have a boilingpoint of from about 30° C. to about 100° C. Any suitable organic solventcan also be used as a phase or solvent inversion agent. The organicsolvent can be used in an amount of from about 1% by weight to about 25%by weight of the resin, such as from about 5% by weight to about 20% byweight of the resin, or from about 10% by weight of the resin to about15% by weight of the resin.

A neutralizing agent can be contacted with the resin in the resincomposition to, for example, neutralize acid groups in the resins. Theneutralizing agent can be contacted with the resin as a solid or in anaqueous solution. The neutralizing agent herein can also be referred toas a “basic neutralization agent.” Any suitable basic neutralizationreagent can be used in accordance with the present disclosure.

Suitable basic neutralization agents include both inorganic basic agentsand organic basic agents. Suitable basic agents include, for example,ammonium hydroxide, potassium hydroxide, sodium hydroxide, sodiumcarbonate, sodium bicarbonate, lithium hydroxide, potassium carbonate,potassium bicarbonate, combinations thereof, and the like. Suitablebasic agents also include monocyclic compounds and polycyclic compoundshaving at least one nitrogen atom, such as, for example, secondaryamines, which include aziridines, azetidines, piperazines, piperidines,pyridines, pyridine derivatives, bipyridines, terpyridines,dihydropyridines, morpholines, N-alkylmorpholines,1,4-diazabicyclo[2.2.2]octanes, 1,8-diazabicycloundecanes,1,8-diazabicycloundecenes, dimethylated pentylamines, trimethylatedpentylamines, triethyl amines, triethaholamines, diphenyl amines,diphenyl amine derivatives, poly(ethylene amine), poly(ethylene aminederivatives, amine bases, pyrimidines, pyrroles, pyrrolidines,pyrrolidinones, indoles, indolines, indanones, benzindazones,imidazoles, benzimidazoles, imidazolones, imidazolines, oxazoles,isoxazoles, oxazolines, oxadiazoles, thiadiazoles, carbazoles,quinolines, isoquinolines, naphthyridines, triazines, triazoles,tetrazoles, pyrazoles, pyrazolines, and combinations thereof. Themonocyclic and polycyclic compounds can be unsubstituted or substitutedat any carbon position on the ring.

The basic agent can be used as a solid such as, for example, sodiumhydroxide flakes, so that it is present in an amount of from about0.001% by weight to 50% by weight of the resin, such as from about 0.01%by weight to about 25% by weight of the resin, or from about 0.1% byweight to 5% by weight of the resin.

As noted above, the basic neutralization agent can be added to a resinpossessing acid group. The addition of the basic neutralization agentmay thus raise the pH of an emulsion including a resin possessing acidgroup to a pH of from about 5 to about 12, in embodiments, from about 6to about 11. The neutralization of the acid groups can enhance formationof the emulsion.

The neutralization ratio can be from about 25% to about 500%, such asfrom about 50% to about 450%, or from about 100% to about 400%.

Surfactant

As discussed above, a surfactant can be contacted with the resin priorto formation of the resin composition used to form the latex emulsion.One, two, or more surfactants can be used. The surfactants can beselected from ionic surfactants and nonionic surfactants. The latex forforming the resin used in forming a toner can be prepared in an aqueousphase containing a surfactant or co-surfactant, optionally under aninert gas such as nitrogen. Surfactants used with the resin to form alatex dispersion can be ionic or nonionic surfactants in an amount offrom about 0.01 to about 15 weight percent of the solids, such as fromabout 0.1 to about 10 weight percent of the solids.

Anionic surfactants that can be used include sulfates and sulfonates,sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate, sodiumdodecylnaphthalene sulfate, dialkyl benzenealkyl sulfates andsulfonates, acids such as abietic acid available from Aldrich, NEOGEN®,NEOGEN SC™ obtained from Daiichi Kogyo Seiyaku Co., Ltd., combinationsthereof, and the like. Other suitable anionic surfactants include,DOWFAX™ 2A1, an alkyldiphenyloxide disulfonate from The Dow ChemicalCompany, and/or TAYCA POWER BN2060 from Tayca Corporation (Japan), whichare branched sodium dodecyl benzene sulfonates. Combinations of thesesurfactants and any of the foregoing anionic surfactants can be used.

Examples of cationic surfactants include, but are not limited to,ammoniums, for example, alkylbenzyl dimethyl ammonium chloride, dialkylbenzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride,alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammoniumbromide, benzalkonium chloride, C12, C15, C17 trimethyl ammoniumbromides, combinations thereof, and the like. Other cationic surfactantsinclude cetyl pyridinium bromide, halide salts of quaternizedpolyoxyethylalkylamines, dodecylbenzyl triethyl ammonium chloride,MIRAPOL and ALKAQUAT available from Alkaril Chemical Company, SANISOL(benzalkonium chloride), available from Kao Chemicals, combinationsthereof, and the like. A suitable cationic surfactant includes SANISOLB-50 available from Kao Corp., which is primarily a benzyl dimethylalkonium chloride.

Examples of nonionic surfactants include, but are not limited to,alcohols, acids and ethers, for example, polyvinyl alcohol, polyacrylicacid, methalose, methyl cellulose, ethyl cellulose, propyl cellulose,hydroxyl ethyl cellulose, carboxy methyl cellulose, polyoxyethylenecetyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether,polyoxyethylene octylphenyl ether, polyoxyethylene oleyl ether,polyoxyethylene sorbitan monolaurate, polyoxyethylene stearyl ether,polyoxyethylene nonylphenyl ether, dialkylphenoxy poly(ethyleneoxy)ethanol, combinations thereof, and the like. Commercially availablesurfactants from Rhone-Poulenc such as IGEPAL CA-210™, IGEPAL CA-520™,IGEPAL CA-720™, IGEPAL CO-890™, IGEPAL CO-720™, IGEPAL CO-290™, IGEPALCA-210™, ANTAROX 890™ and ANTAROX 897™ can be used.

The choice of particular surfactants or combinations thereof, as well asthe amounts of each to be used, are within the purview of those skilledin the art.

Preparation of Toner

A latex emulsion can be used to form a toner, such as an EA toner. Thelatex emulsion can be added to a pre-toner mixture, such as beforeparticle aggregation in the EA coalescence process. The latex oremulsion, as well as a binder resin, a wax such as a wax dispersion, acolorant, and any other desired or required additives such assurfactants, may form the pre-toner mixture.

The pre-toner mixture can be prepared, and the pH of the resultingmixture can be adjusted, by an acid such as, for example, acetic acid,nitric acid or the like. The pH of the mixture can be adjusted to befrom about 4 to about 5, although a pH outside this range can be used.Additionally, the mixture can be homogenized. If the mixture ishomogenized, homogenization can be accomplished by mixing at a mixingspeed of from about 600 to about 4,000 revolutions per minute, althoughspeeds outside this range can be used. Homogenization can beaccomplished by any suitable means, including, for example, an IKA ULTRATURRAX T50 probe homogenizer.

Aggregation

Following the preparation of the above mixture, including the additionor incorporation into the pre-toner mixture of the latex emulsionproduced by the methods disclosed herein, an aggregating agent can beadded to the mixture. Any suitable aggregating agent can be used to forma toner. Suitable aggregating agents include, for example, aqueoussolutions of a divalent cation or a multivalent cation material. Theaggregating agent can be, for example, polyaluminum halides such aspolyaluminum chloride (PAC), or the corresponding bromide, fluoride, oriodide, polyaluminum silicates such as polyaluminum sulfosilicate(PASS), and water soluble metal salts including aluminum chloride,aluminum nitrite, aluminum sulfate, potassium aluminum sulfate, calciumacetate, calcium chloride, calcium nitrite, calcium oxylate, calciumsulfate, magnesium acetate, magnesium nitrate, magnesium sulfate, zincacetate, zinc nitrate, zinc sulfate, zinc chloride, zinc bromide,magnesium bromide, copper chloride, copper sulfate, and combinationsthereof. The aggregating agent can be added to the mixture at atemperature that is below the glass transition temperature (TG) of theresin.

The aggregating agent can be added to the mixture used to form a tonerin an amount of, for example, from about 0.01 percent to about 8 percentby weight, such as from about 0.1 percent to about 1 percent by weight,or from about 0.15 percent to about 0.8 percent by weight, of the resinin the mixture, although amounts outside these ranges can be used. Theabove can provide a sufficient amount of agent for aggregation.

To control aggregation and subsequent coalescence of the particles, theaggregating agent can be metered into the mixture over time. Forexample, the agent can be metered into the mixture over a period of fromabout 5 to about 240 minutes, such as from about 30 to about 200minutes, although more or less time can be used as desired or required.The addition of the agent can occur while the mixture is maintainedunder stirred conditions, such as from about 50 revolutions per minuteto about 1,000 revolutions per minute, or from about 100 revolutions perminute to about 500 revolutions per minute, although speeds outsidethese ranges can be used. The addition of the agent can also occur whilethe mixture is maintained at a temperature that is below the glasstransition temperature of the resin discussed above, such as from about30° C. to about 90° C., or from about 35° C. to about 70° C., althoughtemperatures outside these ranges can be used.

The particles can be permitted to aggregate until a predetermineddesired particle size is obtained. A predetermined desired size refersto the desired particle size to be obtained as determined prior toformation, and the particle size being monitored during the growthprocess until such particle size is reached. Samples can be taken duringthe growth process and analyzed, for example with a Coulter Counter, foraverage particle size. The aggregation thus can proceed by maintainingthe elevated temperature, or slowly raising the temperature to, forexample, from about 30° C. to about 99° C., and holding the mixture atthis temperature for a time from about 0.5 hours to about 10 hours, suchas from about hour 1 to about 5 hours (although times outside theseranges may be utilized), while maintaining stirring, to provide theaggregated particles. Once the predetermined desired particle size isreached, then the growth process is halted. The predetermined desiredparticle size can be within the desired size of the final tonerparticles.

The growth and shaping of the particles following addition of theaggregation agent can be accomplished under any suitable conditions. Forexample, the growth and shaping can be conducted under conditions inwhich aggregation occurs separate from coalescence. For separateaggregation and coalescence stages, the aggregation process can beconducted under shearing conditions at an elevated temperature, forexample, of from about 40° C. to about 90° C., such as from about 45° C.to about 80° C. (although temperatures outside these ranges may beutilized), which can be below the glass transition temperature of theresin as discussed above.

Once the desired final size of the toner particles is achieved, the pHof the mixture can be adjusted with a base to a value of from about 3 toabout 10, such as from about 5 to about 9, although a pH outside theseranges may be used.

The adjustment of the pH can be used to freeze, that is to stop, tonergrowth. The base utilized to stop toner growth can include any suitablebase such as, for example, alkali metal hydroxides such as, for example,sodium hydroxide, potassium hydroxide, ammonium hydroxide, combinationsthereof, and the like. In embodiments, ethylene diamine tetraacetic acid(EDTA) may be added to help adjust the pH to the desired values notedabove.

Core—Shell Structure

After aggregation, but prior to coalescence, a resin coating can beapplied to the aggregated particles to form a shell thereover. Any resindescribed above as suitable for forming the toner resin can be used asthe shell.

Resins that can be used to form a shell include, but are not limited to,crystalline polyesters described above, and/or the amorphous resinsdescribed above for use as the core. For example, a polyalkoxylatedbisphenol A-co-terephthalic acid/dodecenylsuccinic acid/trimellitic acidresin, a polyalkoxylated bisphenol A-co-terephthalic acid/fumaricacid/dodecenylsuccinic acid resin, or a combination thereof, can becombined with a polydodecanedioic acid-co-1,9-nonanediol crystallinepolyester resin to form a shell. Multiple resins can be used in anysuitable amounts.

The shell resin can be applied to the aggregated particles by any methodwithin the purview of those skilled in the art. The resins utilized toform the shell can be in an emulsion including any surfactant describedabove. The emulsion possessing the resins can be combined with theaggregated particles described above so that the shell forms over theaggregated particles. In embodiments, the shell may have a thickness ofup to about 5 microns, such as from about 0.1 to about 2 microns, orfrom about 0.3 to about 0.8 microns, over the formed aggregates,although thicknesses outside of these ranges may be obtained.

The formation of the shell over the aggregated particles can occur whileheating to a temperature of from about 30° C. to about 80° C. inembodiments from about 35° C. to about 70° C., although temperaturesoutside of these ranges can be utilized. The formation of the shell cantake place for a period of time of from about 5 minutes to about 10hours, such as from about 10 minutes to about 5 hours, although timesoutside these ranges may be used.

For example, the toner process can include forming a toner particle bymixing the polymer latexes, in the presence of a wax dispersion and acolorant with an optional coagulant while blending at high speeds. Theresulting mixture having a pH of, for example, of from about 2 to about3, can be aggregated by heating to a temperature below the polymer resinTg to provide toner size aggregates. Optionally, additional latex can beadded to the formed aggregates providing a shell over the formedaggregates. The pH of the mixture can be changed, for example, by theaddition of a sodium hydroxide solution, until a pH of about 7 may beachieved.

Coalescence

Following aggregation to the desired particle size and application ofany optional shell, the particles can be coalesced to the desired finalshape. The coalescence can be achieved by, for example, heating themixture to a temperature of from about 45° C. to about 100° C., such asfrom about 55° C. to about 99° C. (although temperatures outside ofthese ranges may be used), which can be at or above the glass transitiontemperature of the resins used to form the toner particles, and/orreducing the stirring, for example, to a stirring speed of from about100 revolutions per minute to about 1,000 revolutions per minute, suchas from about 200 revolutions per minute to about 800 revolutions perminute (although speeds outside of these ranges may be used). The fusedparticles can be measured for shape factor or circularity, such as witha Sysmex FPIA 2100 analyzer, until the desired shape is achieved.

Higher or lower temperatures can be used, it being understood that thetemperature is a function of the resins used for the binder. Coalescencemay be accomplished over a period of from about 0.01 hours to about 9hours, such as from about 0.1 hours to about 4 hours (although timesoutside of these ranges can be used).

After aggregation and/or coalescence, the mixture can be cooled to roomtemperature, such as from about 20° C. to about 25° C. The cooling canbe rapid or slow, as desired. Suitable cooling methods includeintroducing cold water to a jacket around the reactor. After cooling,the toner particles can be washed with water, and then dried. Drying canbe accomplished by any suitable method for drying including, forexample, freeze-drying.

Wax

A wax can be combined with the latex or emulsion, colorant, and the likein forming toner particles. When included, the wax can be present in anamount of, for example, from about 1 weight percent to about 25 weightpercent of the toner particles, such as from about 5 weight percent toabout 20 weight percent of the toner particles, although amounts outsidethese ranges can be used.

Suitable waxes include waxes having, for example, a weight averagemolecular weight of from about 500 to about 20,000, such as from about1,000 to about 10,000, although molecular weights outside these rangesmay be utilized. Suitable waxes include, for example, polyolefins suchas polyethylene, polypropylene, and polybutene waxes such ascommercially available from Allied Chemical and Petrolite Corporation,for example POLYWAX™ polyethylene waxes from Baker Petrolite, waxemulsions available from Michaelman, Inc. and the Daniels ProductsCompany, EPOLENE N-15™ commercially available from Eastman ChemicalProducts, Inc., and VISCOL 550-P™, a low weight average molecular weightpolypropylene available from Sanyo Kasei K. K.; plant-based waxes, suchas carnauba wax, rice wax, candelilla wax, sumacs wax, and jojoba oil;animal-based waxes, such as beeswax; mineral-based waxes andpetroleum-based waxes, such as montan wax, ozokerite, ceresin, paraffinwax, microcrystalline wax, and Fischer-Tropsch wax; ester waxes obtainedfrom higher fatty acid and higher alcohol, such as stearyl stearate andbehenyl behenate; ester waxes obtained from higher fatty acid andmonovalent or multivalent lower alcohol, such as butyl stearate, propyloleate, glyceride monostearate, glyceride distearate, andpentaerythritol tetra behenate; ester waxes obtained from higher fattyacid and multivalent alcohol multimers, such as diethyleneglycolmonostearate, dipropyleneglycol distearate, diglyceryl distearate, andtriglyceryl tetrastearate; sorbitan higher fatty acid ester waxes, suchas sorbitan monostearate, and cholesterol higher fatty acid ester waxes,such as cholesteryl stearate. Examples of functionalized waxes that canbe used include, for example, amines, amides, for example AQUA SUPERSLIP6550™, SUPERSLIP 6530™ available from Micro Powder Inc., fluorinatedwaxes, for example POLYFLUO 190™, POLYFLUO 200™, POLYSILK 19™, POLYSILK14™ available from Micro Powder Inc., mixed fluorinated, amide waxes,for example MICROSPERSION 19™ also available from Micro Powder Inc.,imides, esters, quaternary amines, carboxylic acids or acrylic polymeremulsion, for example JONCRYL 74™, 89™, 130™, 537™, and 538™, allavailable from SC Johnson Wax, and chlorinated polypropylenes andpolyethylenes available from Allied Chemical and Petrolite Corporationand SC Johnson wax. Mixtures and combinations of the foregoing waxes canbe used. Waxes can be included as, for example, fuser roll releaseagents.

Colorant

The toner particles described herein can further include colorant.Colorant includes pigments, dyes, mixtures of dyes, mixtures ofpigments, mixtures of dyes and pigments, and the like made in accordancewith the methods disclosed herein. Suitable colorants include thosecomprising carbon black, such as, REGAL 330® and Nipex 35. Coloredpigments, such as, cyan, magenta, yellow, red, orange, green, brown,blue or mixtures thereof can be used. The additional pigment or pigmentscan be used as water-based pigment dispersions. Suitable colorantsinclude inorganic pigments and organic pigments. Examples of pigmentsinclude SUNSPERSE 6000, FLEXIVERSE and AQUATONE, water-based pigmentdispersions from SUN Chemicals; HELIOGEN BLUE L6900™, D6840™, D7080™,D7020™, PYLAM OIL BLUE™, PYLAM OIL YELLOW™ and PIGMENT BLUE I™ availablefrom Paul Uhlich & Company, Inc.; PIGMENT VIOLET I™, PIGMENT RED 48™,LEMON CHROME YELLOW DCC IO26™, TOLUIDINE RED™ and BON RED C™ availablefrom Dominion Color Corporation, Ltd., Toronto, Ontario; NOVAPERM YELLOWFGL™ and HOSTAPERM PINK E™ from Hoechst; CINQUASIA MAGENTA™ availablefrom E.I. DuPont de Nemours & Co., and the like. Examples of magentapigments include 2,9-dimethyl-substituted quinacridone, an anthraquinonedye identified in the Color Index as CI 60710, CI Dispersed Red 15, adiazo dye identified in the Color Index as CI 26050, CI Solvent Red 19and the like. Illustrative examples of cyan pigments include coppertetra(octadecylsulfonamido) phthalocyanine, a copper phthalocyaninepigment listed in the Color Index as CI 74160, CI Pigment Blue, PigmentBlue 15:3, Pigment Blue 15:4, an Anthrazine Blue identified in the ColorIndex as CI 69810, Special Blue X-2137 and the like. Illustrativeexamples of yellow pigments are diarylide yellow 3,3-dichlorobenzideneacetoacetanilide, a monoazo pigment identified in the Color Index as CI12700, CI Solvent Yellow 16, a nitrophenyl amine sulfonamide identifiedin the Color Index as Foron Yellow SE/GLN, CI Disperse Yellow3,2,5-dimethoxy-4-sulfonanilide phenylazo-4′-chloro-2,5-dimethoxyacetoacetanilide and Permanent Yellow FGL.

Examples of inorganic pigments include such as, Ultramarine violet:(PV15) Silicate of sodium and aluminum containing sulfur; Han Purple:BaCuSi₂O₆; Cobalt Violet: (PV14) cobalt phosphate; Manganese Violet:(PV16) Manganese ammonium phosphate; Ultramarine (PB29): a complexnaturally occurring pigment of sulfur-containing sodio-silicate(Na₈₋₁₀Al₆Si₆O₂₄S₂₋₄); Cobalt Blue (PB28) and Cerulean Blue (PB35):cobalt(II) stannate; Egyptian Blue: a synthetic pigment of calciumcopper silicate (CaCuSi₄O₁₀); Han Blue: BaCuSi₄O₁₀; Prussian Blue(PB27): a synthetic pigment of ferric hexacyanoferrate (Fe₇(CN)₁₈). Thedye Marking blue is made by mixing Prussian Blue and alcohol;YIn_(1-x)Mn_(x)O₃: a synthetic pigment made from inserting Mn into thetrigonal bipyramidal atomic site of the YInO₃ crystal structure. CadmiumGreen: a light green pigment consisting of a mixture of Cadmium Yellow(CdS) and Viridian (Cr₂O₃); Chrome Green (PG17); Viridian (PG18): a darkgreen pigment of hydrated chromium(III) oxide (Cr₂O₃); Paris Green:copper(II) acetoarsenite; (Cu(C₂H₃O₂)₂.3Cu(AsO₂)₂); Scheele's Green(also called Schloss Green): copper arsenite CuHAsO₃; Orpiment naturalmonoclinic arsenic sulfide (As₂S₃); Cadmium Yellow (PY37): cadmiumsulfide (CdS); Chrome Yellow (PY34): natural pigment of lead(II)chromate (PbCrO₄); Aureolin (also called Cobalt Yellow) (PY40):Potassium cobaltinitrite (Na₃Co(NO₂)₆; Yellow Ochre (PY43): a naturallyoccurring clay of hydrated iron oxide (Fe₂O₃.H₂O); Naples Yellow (PY41);Titanium Yellow (PY53); Mosaic gold: stannic sulfide (SnS₂); CadmiumOrange (PO20): an intermediate between cadmium red and cadmium yellow:cadmium sulfoselenide; Chrome Orange: a naturally occurring pigmentmixture composed of lead(II) chromate and lead(II) oxide. (PbCrO₄+PbO);Cadmium Red (PR108): cadmium selenide (CdSe); Sanguine, Caput Mortuum,Venetian Red, Oxide Red (PR102); Burnt Sienna (PBr7): a pigment producedby heating Raw Sienna; Carbon Black (PBk7); Ivory Black (PBk9); VineBlack (PBk8); Lamp Black (PBk6); Titanium Black; Antimony White: Sb₂O₃;Barium sulfate (PW5); Titanium White (PW6): titanium(IV) oxide TiO₂;Zinc White (PW4): Zinc Oxide (ZnO)

Other known colorants can be used, such as, Levanyl Black A-SF (Miles,Bayer) and Sunsperse Carbon Black LHD 9303 (Sun Chemicals), and coloreddyes, such as, Neopen Blue (BASF), Sudan Blue OS (BASF), PV Fast BlueB2G 01 (American Hoechst), Sunsperse Blue BHD 6000 (Sun Chemicals),Irgalite Blue BCA (CibaGeigy), Paliogen Blue 6470 (BASF), Sudan III(Matheson, Coleman, Bell), Sudan II (Matheson, Coleman, Bell), Sudan IV(Matheson, Coleman, Bell), Sudan Orange G (Aldrich), Sudan Orange 220(BASF), Paliogen Orange 3040 (BASF), Ortho Orange OR 2673 (Paul Uhlich),Paliogen Yellow 152, 1560 (BASF), Lithol Fast Yellow 0991K (BASF),Paliotol Yellow 1840 (BASF), Neopen Yellow (BASF), Novoperm Yellow FG 1(Hoechst), Permanent Yellow YE 0305 (Paul Uhlich), Lumogen Yellow D0790(BASF), Sunsperse Yellow YHD 6001 (Sun Chemicals), Suco-Gelb L1250(BASF), SUCD-Yellow D1355 (BASF), Hostaperm Pink E (American Hoechst),Fanal Pink D4830 (BASF), Cinquasia Magenta (DuPont), Lithol ScarletD3700 (BASF), Toluidine Red (Aldrich), Scarlet for Thermoplast NSD PS PA(Ugine Kuhlmann of Canada), E.D. Toluidine Red (Aldrich), Lithol RubineToner (Paul Uhlich), Lithol Scarlet 4440 (BASF), Bon Red C (DominionColor Company), Royal Brilliant Red RD-8192 (Paul Uhlich), Oracet PinkRF (Ciba-Geigy), Paliogen Red 3871K (BASF), Paliogen Red 3340 (BASF),Lithol Fast Scarlet L4300 (BASF), combinations of the foregoing and thelike. Other pigments that can be used, and which are commerciallyavailable include various pigments in the color classes, Pigment Yellow74, Pigment Yellow 14, Pigment Yellow 83, Pigment Orange 34, Pigment Red238, Pigment Red 122, Pigment Red 48:1, Pigment Red 269, Pigment Red53:1, Pigment Red 57:1, Pigment Red 83:1, Pigment Violet 23, PigmentGreen 7 and so on, and combinations thereof.

The colorant, for example carbon black, cyan, magenta and/or yellowcolorant, may be incorporated in an amount sufficient to impart thedesired color to the toner. In general, pigment or dye, may be employedin an amount ranging from about 2% to about 35% by weight of the tonerparticles on a solids basis, from about 5% to about 25% by weight orfrom about 5% to about 15% by weight.

In embodiments, more than one colorant may be present in a tonerparticle. For example, two colorants may be present in a toner particle,such as, a first colorant of pigment blue, may be present in an amountranging from about 2% to about 10% by weight of the toner particle on asolids basis, from about 3% to about 8% by weight or from about 5% toabout 10% by weight; with a second colorant of pigment yellow that maybe present in an amount ranging from about 5% to about 20% by weight ofthe toner particle on a solids basis, from about 6% to about 15% byweight or from about 10% to about 20% by weight and so on.

Other Additives

The toner particles can contain other optional additives, as desired orrequired. For example, the toner can include positive or negative chargecontrol agents, for example, in an amount of from about 0.1 to about 10percent by weight of the toner, such as from about 1 to about 3 percentby weight of the toner (although amounts outside of these ranges may beused). Examples of suitable charge control agents include quaternaryammonium compounds inclusive of alkyl pyridinium halides; bisulfates;alkyl pyridinium compounds, including those disclosed in U.S. Pat. No.4,298,672, the disclosure of which is hereby incorporated by referencein its entirety; organic sulfate and sulfonate compositions, includingthose disclosed in U.S. Pat. No. 4,338,390, the disclosure of which ishereby incorporated by reference in its entirety; cetyl pyridiniumtetrafluoroborates; distearyl dimethyl ammonium methyl sulfate; aluminumsalts such as BONTRON E84™ or E88™ (Orient Chemical Industries, Ltd.);combinations thereof, and the like. Such charge control agents can beapplied simultaneously with the shell resin described above or afterapplication of the shell resin.

External additive particles can be blended with the toner particlesafter formation including flow aid additives, which additives can bepresent on the surface of the toner particles. Examples of theseadditives include metal oxides such as titanium oxide, silicon oxide,aluminum oxides, cerium oxides, tin oxide, mixtures thereof, and thelike; colloidal and amorphous silicas, such as AEROSILR™, metal saltsand metal salts of fatty acids inclusive of zinc stearate, calciumstearate, or long chain alcohols such as UNILIN 700, and mixturesthereof.

In general, silica can be applied to the toner surface for toner flow,tribo enhancement, admix control, improved development and transferstability, and higher toner blocking temperature. TiO₂ may be appliedfor improved relative humidity (RH) stability, tribo control andimproved development and transfer stability. Zinc stearate, calciumstearate and/or magnesium stearate can be used as an external additivefor providing lubricating properties, developer conductivity, triboenhancement, enabling higher toner charge and charge stability byincreasing the number of contacts between toner and carrier particles. Acommercially available zinc stearate known as Zinc Stearate L, obtainedfrom Ferro Corporation, can be used. The external surface additives canbe used with or without a coating.

Each of these external additives can be present in an amount of fromabout 0.1 percent by weight to about 5 percent by weight of the toner,such as from about 0.25 percent by weight to about 3 percent by weightof the toner, although the amount of additives can be outside of theseranges. The toners may include, for example, from about 0.1 weightpercent to about 5 weight percent titanium dioxide, such as from about0.1 weight percent to about 8 weight percent silica, or from about 0.1weight percent to about 4 weight percent zinc stearate (although amountsoutside of these ranges may be used). Suitable additives include thosedisclosed in U.S. Pat. Nos. 3,590,000, 3,800,588, and 6,214,507, thedisclosures of each of which are hereby incorporated by reference intheir entirety. Again, these additives can be applied simultaneouslywith the shell resin described above or after application of the shellresin.

The toner particles can have a weight average molecular weight (Mw) inthe range of from about 17,000 to about 80,000 daltons, a number averagemolecular weight (Mn) of from about 3,000 to about 10,000 daltons, and aMWD (a ratio of the Mw to Mn of the toner particles, a measure of thepolydispersity, or width, of the polymer) of from about 2.1 to about 10(although values outside of these ranges can be obtained).

While the description above refers to particular embodiments, it will beunderstood that many modifications may be made without departing fromthe spirit thereof. The accompanying claims are intended to cover suchmodifications as would fall within the true scope and spirit ofembodiments herein.

The presently disclosed embodiments are, therefore, to be considered inall respects as illustrative and not restrictive, the scope ofembodiments being indicated by the appended claims rather than theforegoing description. All changes that come within the meaning of andrange of equivalency of the claims are intended to be embraced therein.

EXAMPLES

The example set forth herein below is illustrative of differentcompositions and conditions that can be used in practicing the presentembodiments. All proportions are by weight unless otherwise indicated.It will be apparent, however, that the embodiments can be practiced withmany types of compositions and can have many different uses inaccordance with the disclosure above and as pointed out hereinafter.

The embodiments will be described in further detail with reference tothe following examples and comparative examples. All the “parts” and “%”used herein mean parts by weight and % by weight unless otherwisespecified.

Comparative Example

This comparative example was done as control to show original particlesize and particle size distribution of pigment particles. Into a 15 mlvial was added 0.5 g of carbon black pigment powder REGAL 330®, 5 g ofdeionized water (DIW), and 0.24 g (18.75 wt %) Tayca power aqueoussolution. The vial was then kept and shook for about 2 min (at this stepa certain degree of milling/mixing has been provided). The particle sizeof pigment was measured with a small value peak at ˜133 nm and a largevalue peak at ˜417 nm as shown in FIG. 3.

Example

This example was prepared with the magnetic actuated milling of thepresent embodiments. Into a 15 ml vial was added 0.5 g of carbon blackpigment powder REGAL 330®, 5 g of DIW, and 0.24 g (18.75 wt %) Taycapower aqueous solution. Thereafter, 0.52 g of micro magnetic particles(Carbonyl Iron Powder from Royalink Industries Corp., average particlesize about 4 to 5 μm) was introduced. In this example, a permanentmagnet was manually moved up and down to provide a cyclic magneticfield. The cyclic frequency is about 1 Hz and total about 50 cycles wereused. Finally, micro magnetic particles were attracted and collected bymagnet before sending the sample for analysis. The particle size ofpigment was measured as shown in FIG. 4.

As can be seen from FIGS. 3 and 4, both size reduction and uniformitywas significantly increased with the present embodiments. Morespecifically, the figures show that without 1 minute of the magneticactuating process, the pigment particles show bimodal distribution withabout 24% of pigment particles having average particles about 417 nm,while with magnetic mixing/milling, the pigment particles is monodistributed with average particle size of 143.7 nm<150 nm.

It will be appreciated that several of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also thatvarious presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims. Unless specifically recited in aclaim, steps or components of claims should not be implied or importedfrom the specification or any other claims as to any particular order,number, position, size, shape, angle, color, or material.

What is claimed is:
 1. A method for preparing a pigment dispersion,comprising: a) adding a pigment, a surfactant, and a solvent into animpellerless vessel; b) adding magnetic particles into the impellerlessvessel; and c) applying a varying magnetic field in a circular motion ona micro or nano scale to move the magnetic particles to mill downpigment particle size, in the impellerless vessel.
 2. The method ofclaim 1, wherein the pigment is selected from the group consisting oftitanium oxide, rouge, chromium oxide, Prussian blue, ultramarine blue,molybdate orange, chrome yellow, and combinations thereof.
 3. The methodof claim 1, wherein the pigment is selected from the group consisting ofcarbon black, titanium dioxide, Pigment Yellow 180, Pigment Yellow 12,Pigment Yellow 13, Pigment Yellow 17, Pigment Blue 15, Pigment Blue15:3, Pigment Red 81:1, Pigment Red 81:2, Pigment Red 81:3, PigmentYellow 74, Pigment Yellow 14, Pigment Yellow 83, Pigment Orange 34,Pigment Red 238, Pigment Red 122, Pigment Red 48:1, Pigment Red 269,Pigment Red 53:1, Pigment Red 57:1, Pigment Red 83:1, Pigment Violet 23,Pigment Green 7, and combinations thereof.
 4. The method of claim 1,wherein the pigment is selected from the group consisting of aphthalocyanine-based pigment, an insoluble azo-based pigment, an azolake-based pigment, an anthraquinone-based pigment, a quinacridone-basedpigment, a dioxazine-based pigment, a diketopyrrolopyrrol-based pigment,an anthrapyrimidine-based pigment, an anthanethrone-based pigment, anindanthrone-based pigment, a flavanthrone-based pigment, aperinone-based pigment, a perylene-based pigment, a thioindigo-basedpigment, a quinophthalone-based pigment, and combinations thereof. 5.The method of claim 1, wherein the solvent is selected from the groupconsisting of water, organic solvent, and mixtures thereof.
 6. Themethod of claim 1, wherein the surfactant is selected from the groupconsisting of anionic surfactants, nonionic surfactants, cationicsurfactants, and combinations thereof.
 7. The method of claim 1, furthercomprising collecting the magnetic particles for re-using at a latertime.
 8. The method of claim 1, wherein the magnetic particles arecomprised of a, paramagnetic, ferrimagnetic, ferromagnetic orantiferromagnetic material.
 9. The method of claim 1, wherein themagnetic particles have a non-magnetic coating.
 10. The method of claim1, wherein the magnetic particles have a particle diameter size of fromabout 5 nm to about 50 microns.
 11. The method of claim 1, wherein themagnetic field has a strength of from about 500 Gauss to about 20,000Gauss.
 12. The method of claim 1, wherein the magnetic field is appliedthrough one or more electromagnets.
 13. The method of claim 1, whereinthe magnetic field is applied in a circular, an up and down, a right andleft motion, triangular motion, and mixtures thereof.
 14. The method ofclaim 1, wherein a reduced size of the pigment particle is from about 5nm to about 300 nm.
 15. The method of claim 1, wherein the varyingmagnetic field is applied by moving a permanent magnet.
 16. A system forpreparing a pigment dispersion, comprising: a) a vessel for holding asolution comprising pigment particles, a surfactant and a solvent; b)magnetic particles added to the solution; c) a source for applying avarying magnetic field in a circular motion on a micro or nano scale tomove the magnetic particles to mill down pigment particle size; and d) acollector for collecting the magnetic particles for re-using at a latertime; wherein the system lacks an impeller thereby allowing the vesselto take on any geometric design.
 17. The system of claim 16, wherein thesource for applying the magnetic field is one or more electromagnets.18. The system of claim 16, wherein the magnetic particles are selectedfrom a group of, paramagnetic, ferrimagnetic, ferromagnetic orantiferromagnetic material.
 19. The system of claim 16, wherein themagnetic particles have a particle diameter size of from about 5 nm toabout 50 μm.